package com.company.test20;

import java.math.BigInteger;

/**
 * Created by Administrator on 2016.9.26.
 */
public class Test2001 {
    public static void main(String[] args){
        System.out.println(sum(1000).toString());
    }

    private static BigInteger sum(int number){
        if(number==1){
            return new BigInteger("1");
        }else {
            return sum(number-1).multiply(new BigInteger(number+""));
        }
    }
}
